Esters of n, nu-bis(2-cyanoethyl) carboxamic acids



United tates Patent (3 M 2,837,557 ESTERS F N,N-BIS(2-CYANOETHYL)CARBOXAMIC ACIDS John W. Lynn, Charleston, W. Va., assignor to UnionCarbide Corporation, a corporation of New York No Drawing. Originalapplication April 22, 1953, Serial No. 350,514, now Patent No.2,7Q0,820, dated April 30, 1957. Divided and this application June 5,1956, Serial No. 589,366

1 Claim. (Cl. 260-4654) usually necessary to add a plasticizer to makethe resins soft, pliable and capable of being milled into strong,pliable sheets or films. It is also advantageous that the plasticizedresin compositions have heat stability, suppleness and elasticity. Inorder for a material to be useful as a plasticizer, it is necessary thatit be compatible with the resin and not exude or sweat out, leaving theresin unplasticized. Therefore, it is an object of my invention toprovide compounds of the class described above which are improvedplasticizers for polyvinyl resins.

The compounds of my invention are useful in plasticizing vinyl resins,including, for example, the vinyl chloridevinyl acetate resins, thevinyl chloride resins, the vinyl chloride-vinyl acetate-maleic acidresins, the vinyl chloride-acrylonitrile-vinyl acetate resins, and thevinyl chloride-acrylonitrile resins. More particularly, the compoundscomprising my invention are useful in plasticizing vinylchloride-acrylonitrile copolymers.

My new compounds impart excellent flexibility characteristics to resincompositions, and, more particularly, the use of my new compounds withvinyl chloride-acrylonitn'le resin compositions makes possibleadditional uses of vinyl chloride-acrylonitrile plasticized compositionsin the fields of cloth coatings, paper coatings, metal coatings, wirecoatings, calandered sheets and molded articles Where low-temperatureflexibility is an important feature.

The new compounds may be synthesized by reacting the cyclic anhydride ofa dibasic acid with di(2-cyanoethyl) amine and then esterifying theresulting N,N-bis (2- cyanoethyl) carboxamic acid with an alcohol. Thestarting material, di(2-cyanoethyl) amine, may be readily prepared bythe reaction of acrylonitrile with ammonia.

The reaction of di(2-cyancethyl) amine with the cyclic anhydride of thedicarboxylic acid gives the corresponding N,N-bis(2-cyanoethyl)carboxamic acid in excellent yield. Esterification of these amic acidswith alcohols produces the esters of the N,N-bis(2-cyanoethyl)carboxamic acids.

The reaction whereby the N,N-bis(2-cyanoethyl) carboxamic acid estersare produced in accordance with my invention may be written as follows:

H C C n 2 N): (11+) n 2,837,557 Patented June 3, 1958 2' l radical and Rrepresents a hydrocarbon radical corresponding to the alcohol used inthe esterification reaction.

The acids of the type above defined do not appear in the prior art andare therefore new compounds forming a part of this invention.

In general, these acids may be prepared by adding di(2 cyanoethyl) amineslowly to a slurry of the cyclic anhydride in benzene at a temperaturein the range of 50 C. to 80 C. The mixture is then stirred at the refluxtemperature for a short period of time. Upon cooling, theN,N-bis(2-cyanoethyl) carboxamic acids are crystallized from thesolution.

The N,N-bis(2-cyanoethyl) carboxamic acids are colorless crystallinesolids, soluble to a limited amount. in water and alcohols, quiteinsoluble in hydrocarbons and were unstable at moderately hightemperatures. I

The esters of the N,N-bis(2-cyanoethyl) carboxamic acids can be preparedby esterification of the isolated and purified amic acid or by directesterification of the crude amic acid. The Water formed during theesterification reaction can be removed by azeotropic distillation, orother known expedients. The esters are usually taken as residueproductsafter steam-stripping to remove the volatile byproducts.

The cyclic anhydrides employed in the preparation of theN,N-bis(2-cyanoethyl) carboxamic acids can be any aliphatic dicarboxylicacid anhydride. The anhydrides include, for example, succinic anhydride,glutaric anhydride and adipic anhydride. The anhydrides employed in thepreparation of the amic acids also include the anhydrides of theunsaturated dicarboxylic acids, such as, for example, maleic anhydride.V

The alcohols employed in the esterification reaction may be any of thetypical monohydric and polyhydric alcohols, including both aliphatic andaromatic alcohols, such as, for example, methanol, ethanol, isopropanol,butanol, '2-ethylb'utanol, 2-ethylhexanol, allyl; alcohol, furfurylalcohol, tetrahydrofurfuryl alcohol, benzyl alcohol, and diethyleneglycol.

In its broadest aspects, my invention .is directed to the esters ofN,N-bis(2-cyanoethy1) carboxamic acids having the general formula:

wherein R represents a divalent, aliphatic hydrocarbon radical and Rrepresents an aliphatic hydrocarbon radical.

More specifically, my invention is directed to the esters ofN,N-bis(2-cyanoethyl) carboxarnic acids having the general formula: i

wherein R represents an aliphatic hydrocarbon radical and n representsan integer in the range 2 through 4.

In its specific aspects, my invention is directed to the esters ofN,N-bis(2-cyanoethyl) carboxamic acids having wherein R represents adivalent aliphatic hydrocarbon the general formula:

3 Example 1 vNJtI-BIS(Z-CYANOE'IPHYI SUCCINAMIC ACID A mixture ofsuccinic anhydride mols) and benzene was refluxed andB,B-iminodipropionitrile (di(cyanoethyl)amine) (5 mols) Was slowlyadded. The mixture was heated for one hour and then allowed to cool andcrystallize. The solid product was removed and crystallized fromethanol. The N,N-bis(2-cyanoethyl) succinamic acid was obtained in 92.6percent yield as colorless crystals melting at 118-119 C. The productcontained 18.73 percent N, which corresponds to the theoretical value of18.83 percent N, determined from the theoretical chemical analysis ofthe product.

7 Example 2 N,N-BIS (Z-CYANOETHYL) MALEAMIC ACID "To a mixture of maleicanhydride (1 mol) in benzene at are reflux, B,B'-iminodipropionitrile (1mol) was added slowly while stirring. After heating one hour, themixture was allowed to cool and crystallize. The solid product was thencrystallized from ethanol. The N,N- bis(2-.c yanoethyl) maleamic acidwas obtained in 91 percent yield as colorless crystals melting at 140141C. The product contained 18.91 percent N, which compares fayorably withthe theoretical value of 19.0 percent N determined from the theoreticalchemical analysis.

Esterification of this type of carboxylic acid is considerably moredifiicult than would be expected. In fact the N,N-bis(2-cyanoethyl)maleamic acid was totally resistant to normal esterification. Thisextreme lack of reactivity is attributed to steric hindrance caused bythe eyanoethyl groups held in a fixed cis configuration to the carboxygroup under attack. Fisher-Hirschfelder molecular models clearlydemonstrate this shielding effect. A further fact strengthening thisview is that when dry hydrochloric acid is used as a catalyst (seeExample 13) the maleamic acid was esterified. The hydrochloric acidfirst catalyzed the isomerization of the cis-maleic form to thetrans-fumaric form, which could then be esterified with no sterichindrance.

Example 3 N ,N-BIS(2-CYANOETHYL) GLUTARAMIC ACID Example 4 N,N-BIS(2-CYANOETHYLAZEELUORENYLSUCCINAMIC An equimolar quantity ofB,B'-iminodipropionitrile was reacted for one hour at 50 C. in benzenesolution with 9-fluorenylsuccinic anhydride having the formula:

CH-O

On cooling, the amic acid crystallized and was removed andrecrystallized from aqueous ethanol. An 83 percent yield ofN,N-bis(2-cyanoethyl)-9-fluorenylsuccinamic acid was obtained ascolorless crystals melting at 140 --141 C.

OHPC

Example 5 ETHYL N,N-BIS (2-CYA'NOETHYL) SUCCINAMATE A mixture ofN,N-bis(2-cyanoethyl) succinamic acid (0.5 mol), ethanol (1.1 mol),sulfuric acid (l gram) and 250 ml. of benzene were refluxed for 8 hours,the water formed being removed azeotropically. After washing thereaction mixture with sodium carbonate, the solvent was removed. EthylN,N-bis(2-cyanoethyl) succinamate was obtained in 81 percent yield as aresidue product. The product contained 16.68 percent N, as compared withthe theoretical value of 16.73 percent N and had a refractive index (nof 1.4788.

Example 7 ISOPROPYL N,N-BIS(2-CYANOETHYL) SUCCINAMATE A mixture ofN,N-bis(2-cyanoethyl) succinamic acid (0.5 mol), isopropanol (0.5 mol),sulfuric acid (1 gram) and 300 ml. of benzene was refluxed for 16 hourswhile the water formed was removed azeotropically. The reaction mixturewas Washed with sodium carbonate solution and the solvent was removed.lsopropyl N,N-bis(2- cyanoethyl) succinamate was obtained in 55 percentyield as a viscous amber oil, which crystallized on long standing to asolid melting at 45 -47 C. The product contained 15.23 percent N, ascompared with the theoretical value of 15.86 percent N, and had arefractive index (n of 1.4747.

Example 8 B'UTYL N,N-BIS(2-CYANOETHYL) SUCCINAMATEB,B'-iminodipropionitrile (2 mols) was added slowly to a stirredsupension of succinic anhydride (2.1 mols) in refluxing benzene and themixture reacted for one hour. Butanol (3 mols) and sulfuric acid (1gram) were added and the mixture refluxed for 8 hours, while removingthe water formed azeotropically. The reaction mixture was extracted withsodium carbonate solution and the solvent removed. ButylN,N-bis(2-cyanoethyl) succinamate was obtained in 92, percent yield as aviscous amber colored residue product. The product contained 60.15percent C; 7.65 percent H; and 15.38 percent N, as compared to thetheoretical chemical analysis of 60.18 percent C; 7.59 percent H; and15.05 percent N, and had a refractive index of 1.4767.

Example 9 2-ETHYLBU'1YL iN,N-BIS (Z-CYANOETHYL) SUCCINAMATE A mixture ofN,N-bis(2-cyanoethyl) succinarnic acid (0.5 mol), Z-ethylbutanol (0.5mol), sulfuric acid (5 grams) and 300 ml. of benzene was refluxed for 14hours, while removing the water formed azeotropically. The reactionmixture was washed with sodium carbonate solution and the solventremoved. Z-ethylbutyl' N,N-bis(2- cyanoethyl) succinarnate was obtainedin 99 percent yield as a dark colored viscous residue product. Theproduct contained 13.27 percent N, which corresponds to the theoreticalvalue of 13.67 percent N and had a refractive index (n m) of 1.4763.

Example Z-ETHYLHEXYL N,N-BIS Z-CYANOETHYL) SUCCINA1 TE A mixture ofN,N-bis(2-cyanoethyl) succinamic acid (0.5 mol), 2-ethylhexanol (0.55mol), sulfuric acid (1 gram) and 250 ml. of benzene was refluxed for 12hours, while removing the water formed azeotropically. The reactionmixture was washed with sodium carbonate solution and the solventremoved. Z-ethylhexyl N,N-bis(2- cyanoethyl) succinamate was obtained in70 percent yield as a dark colored residue product. The productcontained 12.38 percent N as compared with the theoretical value of12.54 percent N, and had a refractive index (a of 1.4736.

' Example 11 ALLYL N,N-BIS(2-CYANOETHYL) SUCCINAMATEB,B-iminodipropionitrile (3 mols) was added slowly to a stirredsuspension of succinic anhydride (3 mols) in refluxing benzene and themixture reacted for 2 hours. Allyl alcohol (6 mols) and sulfuric acid (1gram) were added and the mixture refluxed for 13 hours, while the waterformed was removed azeotropically. The reaction mixture was washed withsodium carbonate solution and the solvent removed. Allyl N,Nbis(2-cyanoethy1) succinamate was obtained in 60 percent yield as aviscous amber colored residue product. The product contained 15.5percent N, which corresponds to the theoretical value of 15.9 percent N,and had a refractive index (n of 1.4893.

Example 12 DIETHLENEGLYCOL N,N-BIS(2-CYANOE'1HYL) SUCOINAMATE A mixtureof N,N-bis(2-cyanoethyl) succinamic acid (1.1 mol), diethyleneglycol(0.5 mol), benzene (750 ml.) and sulfuric acid (4 grams) was refluxedfor 16 hours, while removing the water formed azeotropically. Thereaction mixture was washed with sodium carbonate solution and theslovent removed. Diethylenegylcol di-N,N- bis(2-cyanoethyl) succinamatewas obtained in percent yield as a very viscous amber residue product.The

product contained 55.40 percent C; 6.22 percent H; and 15.81 percent N,which corresponds to the theoretical chemical analysis of 55.79 percentC; 6.20 percent H; and 16.27 percent N.

Example 13 ETHYL N,N-BIS(2-CYANOETHYL) FUMARAMATEB,B'-iminodipropionitrile (2 mols) was added slowly to a stirredsuspension of maleic anhydride (2 mols) in refluxing benzene and themixture reacted for 2 hours. Ethanol (4 mols) was added and thernixturerefluxed for 11 hours, while sparging dry hydrogen chloride beneath thesurface and removing the water formed azeotropically. The reactionmixture was filtered and washed with sodium carbonate solution and thenconcentrated. On standing, the residual oil crystallized.Recrystallization from aqueous ethanol gave ethyl N,N-bis(2-cyanoethyl)fumaramate in 26 percent yield as colorless crystals melting at 68 -69C. The product contained 57.87 percent C and 5.98 percent H, whichcorresponds to the theoretical values of 57.81 percent C and 6.02percent H.

(0.4 mol), butanol (0.8 mol), benzene (300 ml.) and p-toluene-sulfonicacid (0.4 gram) was refluxed for 9 hours, while removing the waterformed azeotropically. The reaction mixture was washed with sodiumcarbonate solution and the solvent removed. Butyl N,N-bis(2- cyanoethyl)glutaramate was obtained in 99 percent yield as a viscous dark coloredresidue product. The product contained 62.47 percent C; 7.71 percent H;and 14.29 percent N, which corresponds to the theoretical values of62.92 per. cent C; and 7.61 percent H, and had a refractive index (21 of1.4700.

This application is a division of application, Serial No. 350,514, filedApril 22, 1953, now Patent No. 2,790,820.

What is claimed is:

Allyl N,N-bis (2-cyanoethyl) succinamate.

No references cited.

